Unintentional cider fizz

[cottonwoodks]

We're starting to open up some of the ciders I made with purchased apple juice from a local cidery, and so far, they've all had a really nice fizz to them. They were from gallon batches, and I didn't do a secondary fermentation, just bottled them after the primary (I mean, going from one gallon primary to 7 16 oz bottles). The FG was 0.998, so I thought the fermentation was done, but evidently not. Am I in danger of having bottle bombs here? There can't have been that much left to ferment.

 

[Chalkyt]

If you bottled at 0.998 there shouldn't be any sugar left to ferment so the source of the fizz is a bit of a mystery.

Bottles will generally handle at least 150 psi unless they are really flawed or damaged, so with your numbers a bottle bomb shouldn't happen. Your "nice fizz" might be something like 2 volumes of CO2 which would be a bit under 25 psi at room temperature and result from fermenting 0.004 gravity points of sugar (i.e. bottling at 1.004). Did you add any sugar for carbonation at bottling time?

Occasionally there are reports of beer or soda with normal carbonation turning into bottle bombs from being left in a car in the sun, but this usually results from temperatures over 150F which can generate bottle pressure of 125 psi or so.

 

[cottonwoodks]

No, I didn't add any sugar. The only thing I can think of was that maybe the FG wasn't exactly 0.998. I didn't record the temperature when I took the reading on these first early batches, and it was no doubt considerably warmer than the 60F that the hydrometer is calibrated for, so it could have been a little bit higher. So maybe there was a little bit of sugar left. If the temperature were 80F (and it WAS really hot), then that really would have been 1.000...so enough to make fizz? But hopefully not enough for bombs? The fizz after 10 weeks is pretty similar to the fizz after 2 weeks.

 

[gregbathurst]

Your cider might have gone through MLF in the bottles.

 

[CKuhns]

Depending on the yeast, temperature and residual sugars you definitely can get a little "fizz" even if bottled at 1.000. The SG can drop to as low as 0.996 and that .004 difference is as much as 2.5 volumes of CO2 (Similar to what beer typically is)

Even if 1.000 drop to 0.998 would provide some CO2.

At this point I would keep them in a cool place and enjoy them. I would not be worried about over carbonation.

 

[cottonwoodks]

Depending on the yeast, temperature and residual sugars you definitely can get a little "fizz" even if bottled at 1.000. The SG can drop to as low as 0.996 and that .004 difference is as much as 2.5 volumes of CO2 (Similar to what beer typically is)

Even if 1.000 drop to 0.998 would provide some CO2.

At this point I would keep them in a cool place and enjoy them. I would not be worried about over carbonation.

Cool! I wouldn't mind that at all.....